8. Assume that the plate power input to the power amplifier of a low-level AM
transmitter is 225 watts and the output power is 55 watts.
In an FM transmitter
which is also low-level modulated the power amplifier with the same power input is
capable of producing a maximum power output of
a. 45 to 90 watts.
b. 90 to 135 watts.
c. 135 to 180 watts.
d. 180 to 225 watts.
9. Since class C amplifiers have tuned grid and plate circuits, they often break
into oscillation because of the feedback through interelectrode capacitance.
In
class C amplifiers used in high-frequency FM transmitters, these oscillations are
prevented by
a. using tetrode tubes.
b. decreasing the grid excitation.
c. increasing the Q of the tank circuit.
d. inserting an adjustable capacitor between the plate and grid.
10. A comparison of the single-ended amplifier shown in figure 72 of TM 11-668
and the push-pull amplifier shown in A of figure 74 reveals that the input and
output capacitances across the tank circuits of the push-pull circuit are one half
those in the single-ended circuit.
Since the output voltage of the push-pull
circuit is twice that of the single-ended circuit, what is the relationship between
the two plate load impedances (Z)?
a. Z's of the two circuits are equal.
b. Z of the push-pull circuit is twice that of the single ended.
c. Z of the single-ended circuit is twice that of the push-pull.
d. Z of the push-pull circuit is four times that of the single ended.
11. A circuit that permits a triode to be operated as a power amplifier at high
frequencies without neutralization may be described as having
a. grid-cathode input, plate-cathode output, and grounded cathode.
b. grid-ground input, cathode-ground output, and grounded plate.
c. cathode-ground input, plate-ground output, and grounded grid.
d. grid-cathode input, plate-ground input, and grounded grid.
12. The grid-tank circuit that would be most appropriate for use in a power
amplifier located several feet from the driver is shown in TM 11-668, figure 75,
sketch
33
Previous Page
